Multifluid heat exchanger



Sept 5, 1950 l s. HoLM Erm. 2,521,369

MULTIFLUID HEAT EXCHANGER 3 sheets-Sheet 2 Filed Nov. 3, 1944 INVENToRsSven fa/w BYPeL/Ydmer IIa/rissa 5, 1950 s. HQLM ETAL uULTIFLuIn HEATmaman 3 Sheets-Sheet 3 Filed Nov. 3, 1944 INVENTOR. Sue/r Holm BY Perflilmerlfarlsson Pstenad sept s, 195o 2,521,369 MUL'rmUm HEAT nxcmnclnLSven Holm and Per Hilmer Karlsson, Wellsvillo,

N. Y., assignors to The Air Preheater 'Corporation, New York, N. Y.

Application November 3, 1944, Serial No. 581,768

12 claims. (ci. 257-246) l The present invention relates to heatexchange apparatus and particularly to apparatus in which heat istransferred between three or more streams of iiuid. y

In the embodiments of the invention described herein the invention isincorporated in a plate type heat exchanger through the passages oi'which one iiuid is circulated to be cooled by indirect contact with twoother fluids.

One use contemplated for the apparatus is to cool air to very lowtemperatures using oxygen and nitrogen both at temperaturessubstantially below 0 F. The air entering at a. temperature around 100F. carries a certain amount of water vapor which sublimes to ice at lowtempera-f tures. To dispose of the ice it is necessary to transpose theair and nitrogen streams so that the nitrogen re-evaporates the icedeposited from the air. The apparatus, therefore, works in two cycles,each of which must give the same performance as to heat exchange andpressure drop. The oxygen enters the apparatus at a lower temperaturethan the nitrogen but is required to leave at the same temperature and.therefore, receives heat from both the air andthe nitrogen.

A feature of the invention is a heat exchanger construction in which twoof the streams of fluid may be switched or transposed with respect totheir relation to each other without, however, changing the rate ofheat' transfer among the three iiuids, the pressure drop through theexchanger for any fluid or the direction of iiow thereof. L

The invention will be best understood `upon consideration of thefollowing detailed description of illustrative embodiments thereof whenconsidered in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional elevation of a heat exchanger embodyingthe invention in apparatus having a series of concentric annularpassages;

Figures 2 and 3 are transverse sectional views along the correspondinglydesignated section lines in Figure 1 and illustrate the connections ofinlet and outlet ducts with the passages of the exchanger;

Figures 4 and 4a are sectional views on line 4-4 of Figure 1illustrating the flow of the fluids during the two cycles of operationof the apparatus shown in Figures y1 to 3. v

v sages of the apparatus in Figure 9 with either a larger number ofpassages;

Figure 6 is a fragmentary sectional view on linel the apparatus duringthe second cycle of opera-- tion;

Figure 9 is a transverse sectional view showing another form oiapparatus in which two of the fluids are circulated through a singleannulus in which independent passages are formed; and

Figures 10 and 11 are a sectional elevation and perspective view showingconnection of the pasinlet and outlet headers for the fluids.

r In Figures 1 to 3, the four concentric wall- -members il, i2, Il andil denne a pair of adiacent annular passages I5, il extendinglongitudinally of the apparatus and a similarly disposed centrallylocated channel II. One of the cooling i'iuids (oxygen) enters thecentral channel I1 at one end of the apparatus through an inletconnection Il and is discharged from the opposite end of the exchangerthrough an outlet connection 2l. As shown in Figures 2 and 3 each of theannular passages il, I0 is divided into two semicircular parts by thediametrically located partitions IB; these annuli could be furthersubdivided if desired. At the upper end of the apparatus at the lefthand side air to be cooled enters through an inlet connection 2i whichcommunicates at the left hand or upper side of the partition it with thesection 23 ci the outermost annular passage i5 and at the right hand orlower side of Fig. 2 of the partition il with the section 2B of theinner annular passage.' i8. At the lower end of the apparatus the outletconnection 24 for air commimicates in like man-4 ner with the lower endsof the semi-circular sec-E tions 2l, Il, one in each of the two annuli.The cold nitrogen enters the bottom of the apparatus` at the left handside through an inlet connestion 3l which extends toward the center o!the apparatus but communicates at the ,right hand side ofthe partitionIl only with the section It of the outer annulus I5 and at the left handside of the partition Il with the section Il of the inner annulus. Atthe upper right hand side of the apparatus the nitrogen is dischargedthrough a similarly connected outlet Il which communicates only with theupper ends of thesemi-circular sections 28 and 28, one in each of theannuli Ii, I6. With connections so arranged the air flows eountercurrentwith respect both to nitrogen and oxygen, which is the desiredrelationship for maximum heat transfer.

Plmdamentally the apparatus comprises a plurality of adjacent parallelfluid passages. In the form to be described immediately these -are inthree concentric annuli. By covering the lower halves oi' the diagramsdesignated Figs. 4 and 4a it may be noted that if the air were to iiowin the entire outer annulus in `cycle I and in the intermediate annulusin cycle II, it is evident that the air would .be cooled to a much lowertemperature in cycle II, where it would now between the cold oxygen andthe cold nitrogen. Further. a discrepancy in the diameter of the annulaecould also result in a difference in pressure drop due to difference inmass velocity. When nitrogen flows in the entire intermediate annulus incycle I, the -oxygen does not exchange any heat with the air in thatcycle. When in accordance with Vthe invention the air and nitrogenstreams each flow in one-half or other adjacent fractional sections ofthe same annulus separated by a dividing wall, the total ow area foreach of the two gases is the same in both cycles and the entireapparatus is balanced as to heat exchange relationship in the two cyclessince the relations that exist on one side in one cycle have theircounterparts on the other side in the second cycle. Heat is alsoexchanged at the same rate between the three gases in either cycle. Theair and nitrogen iiow through the apparatus in substantially greateramount than the oxygen; therefore, extended surfaces in the form of ilnsare used in the annulae Il. I6 carrying these gases. The hydraulicdiameter of the channels between dns must be the same for air as fornitrogen because the pressure drop increases inversely as hydraulicdiameter (also called equivalent diameter) is dened as equal to fourtimes the area` of channel divided by the circumference. In heattransfer the hydraulic diameter of a passage depends on whatportion ofits perimeter is' eifective as heat transfer surface, and is defined asfour times the cross-sectional area divided by the portion of-perlmeterthrough which heat exchange takes place. The walls II, I2, I8 and Il aretherefore spaced radially at such distances that the hydraulic diameterof the inner and outer annuli I5, I6 is the same. This applies also toFigs. 6 and 7 wherein the passages Il 2l are of greater radial widththan passages Il and to obtain the same hydraulic di- For the samereason the fins are radially opposite each other in pairs, with the ilnsin passage 3S having the same spacing on the circumference as the finsin passage I5, and the iinsinpassage 8i spacedradiallyoppositeiins inpassage 2l. The rate of heat transfer is inversely proportional to thetwo-tenths power of the hydraulic diameter. It is therefore evident thatby off-setting the flow in the different ananulae the two cycles areequal, whereas if one gas' stream occupies an entire annulus the twocycles would not be equal because the outside of the apparatus is notaheat transfer surface.

h eat loss from the .outside through insulation (not shown) has the sameeffect on temperature of nitrogen and air in both cycles, as canbe seenby study of'Flgures 4 and 4a, which 'the hydraulic diameter. Forpressure drop, the

show that both of these gases contact the same portion of outside shellin both cycles.

'I'he oxygen stream flows through thev apparatus guided by one or morehelically wound ns ll to impart a swirling motion to the uid, whichthereby alternately passes over surface exchanging heat with air ornitrogen. This prevents any temperature stratification of the oxygenstream.

The construction shown in Figs. 8 and '7 embodies the same principlesbut has an additional pair of annular passages concentrically disposedinwardly of the oxygen channel I1. Thus there is an outer pair of`annular passages I5. It outside of the channel I1 and an inner pair ofpassages II and 3i inwardly of the channel I1. The arrangements of theinlet and outlet connections for this apparatus are shown in Figs. 7 and8 wherein an inlet connection such as that for air designated 2I extendsacross the upper ends of all the annular passages but communicates onlywith the alternate semi-circular sections 23, 43 at one side of thepartition Il and with the intermediate sections zi, u at the other sideof the partition Il. Nitrogen flows in aiternate sections 28, 48 andintermediate sections 2l, 48. With this form there is complete baianceof the heat transfer relation of the several fluids as may be noted byexamining Figs. 'I and 8 showing the relationships for both cycles. Thestreams of nitrogen and air, respectively, are always in passages atopposite sides of an intervening wall while the oxygen flowing throughthe channel I1 always has a stream of air at one side and of nitrogen atthe other. .At the lower part of Fig, 7 the air is in the passage 25outwardly of the channel I1, through which the oxygen flows and thenitrogen is in the inner passage section Il. The relation is reversed inthe upper part (Fig. 7) of the apparatus where the nitrogen is in theouter passage section 28 and the air is in the inner passage section 43.When the air is caused to iiow through channels previously fllledwithnitrogen and vice versa, the respective positions of these fluids withrespect to oxygen are changed as indicated in Fig. 8 but .the heattransfer relationships remain the saine.l

With supply and discharge piping connected vas'indicated in Fig. 5, allof the .valves .5l-ll are open when air flows through the passagesections 23, 25 (and Il, ,also Fig. 8) in the rst cycle and nitrogenflows through the sections 28, 28, 46, 48 while all the valves 55-58 areclosed. Conversely, in the second cycle all of the valves 55-58 are openand valves lI-SI are closed when the nitrogen is to flow through'thesemi-circular sections 25', 23; (and Il, II also in Fig. 8). Therelative countercurrent relation of the flow of air to nitrogen andoxygen is maintained in both cycles as the directions of flow are notchanged.

In the construction diagrammatically indicated in Fig. 9 only oneannular passage surrounds the channel I1 through which oxygen flows.This single annular passage, however, is divided by a number of closelyspaced radial partitions 6I into any desired number of arcuate',segments. The inlet and outlet connections to headers 62, are arrangedso that one fluidv such as air flows through alternate passages I3 whilethe other, such as nitrogen, ilows through the intermediate passages 6l.It will be noted that the air is cooled by nitrogen flowing inintermediate channels at eitherside of its flow passages and also by theoxygen in the channel I1 at the inner duid by means of two others whileproviding ior transposing the relations of the treated fluid and one ofthe treating fluids due to the requirements of al process. Likewise, allforms make it possible to-preserve the same overall heat exchangerela.

tionship among the fluids passing through the heat exchanger in thedifferent cycles and maintain the same pressure drop through the-various passages in each cycle of operation.

What we claim is:

l. -A heat exchanger particularly for gaseous media comprising; acylindrical casing interiorly divided by concentric wall membersextending longitudinally thereof to form a pair of adjacent annularpassages; partitions extending longitudinally of said exchanger andsub-dividing each annular passage into a pair of contiguoussemi-circular sections; multiple uid inlet ducts each connectingindividually with a section of one passage at one side of each partitionand with that section of the other passage located at the opposite sideof said partition; similarly connected fluid outlet ducts; means forminga channel located adjacent the inner one vof said annular passages andconcentric therewith; and inlet and outlet ducts connecting with saidchannel at opposite ends thereof.

2. A heat exchanger particularly for gaseous media comprising; meansdefining a plurality of independent parallel passages extending from rndto end of said heat exchanger parallel to its longitudinal axis;partitions extending parallel to the longitudinal axis of said exchangerand subdividing each passage into a pair of adiacent independentsections; multiple fluid inlet ducts each connecting individually withsections of the alternate passages at one side of each parti-- tion andwith sections of the adjacent passages at the opposite side of eachpartition; similarly connected fluid outlet ducts; means forming achannel located between two of said passages and parallel therewith; andinlet and outlet ducts connecting with said channel at opposite endsthereof.

3. A heat exchanger particularly for gaseous media comprising; meansdefining inner and outer pairs of concentric annular passages extendinglongitudinally of said heat exchanger; partitions extendinglongitudinally of said exchanger and sub-dividing each annular passageinto a plurality of adjacent sections; multiple fluid inlet ducts eachconnecting individually with sections of the alternate passages at oneside of each partition and with sections of the intermediate passages atthe opposite side of each partition; similarly connected fluid outletducts; means forming a. cham,

nel located intermediate the inner and outer pairs of passages andconcentric therewith; and inlet and outlet ducts connecting with saidchannel and opposite ends thereof.

4. A heat exchanger particularly for gaseous media comprising; meansdefining inner and outer pairs of concentric annular passages extendinglongitudinally of said exchanger; partitions extending longitudinally ofsaid exchanger and sub-dividing each annular passage into a pair ofcontiguous semi-circular 6 s inlet ducts each connecting individuallywith scctions of the -alternate passages at one side of each partitionand with sections of the intermediaiepassages at the opposite side ofeach partition; similarly connected fluid outlet ducts-Z means formingan annular channel located between the inner and outer pairs of es andconcentric therewith; and inlet and outlet ducts connecting with saidchannel at opposite ends thereof.

45. A heat exchanger as recited ln claim 3 wherein the radial depth ofthe respective passages and channels is such that they have the samehydraulic diameter.

6. A heat exchanger as recited in claim 3 wherein the concentriccircular walls forming said passages and channel are mutually spacedradially of the heat exchanger at distances pro# viding the samehydraulic diameter for all said passages and said channel.

7. A heat exchanger particularly for gaseous media comprising; acylindrical casing interior` ly divided by concentric wall membersextending longitudinally thereof to form a pair of adjacentI annularpassages; partitions extendingy longitudinally of said exchanger andsub-dividing each annular passage into a pair of contiguoussemi-circular sections; an inlet duct for one f and atl the other sideof'said partition withfa semi-circular section of the adjacent annularpassage; an inlet duct for a second fluid connecting with those sectionsof both said annular passages vthat .are contiguous to the sectionsconnected with said first mentioned inlet duct; similarly connectedfluid outlet ducts; means forming a channel located adjacent the innerone-of said' annular passages and concentric therewith; and

inlet and outlet ducts for circulating fluid through said channel inheat exchange relationship simultaneously with said one fluid flowing ina semi-circular section of the adjacent. annular passage and with saidother fluid flowing in the contiguous semi-circular section of said sameannular passage.

8. A heat exchangerv particularly for gaseous media comprising;means-defining a plurality of independent parallel passages extendingfrom end to end of said heat exchanger parallel to its longitudinalaxis; partitions extending parallel to the longitudinal axis of saidexchanger and sub-dividing each passage into a pair of adjacent inde'lpendent sections; an inlet duct for one fluid connecting at one side ofone partition with a section of one passage and at the other side ofsaid partition with a section of the adjacent passage; an inlet duct fora second fluid connecting with those sections of both said passages thatare contiguous to the sections connected with said first mentioned inletduct; similarly connected fluid outlet ducts; means forming a channellocated adjacent one of said passages and parallel therewith; and inletand outlet ducts for circulating fluid through said channel in heatexchange relationship simultaneously with said one fluid flowing in asection of the adjacent passage and with said other fluid flowing in thecontiguous section of the same passage.

9. A heat exchanger particularly for gaseous media. comprising; acylindrical casing interiorly divided by concentric wall membersextending longitudinally thereof to form a pair of adjacent annularpassages; partitions extending longisections; multiple fluid u tudinallyof said exchanger and sub-dividing 7 each annular passage into a pair ofcontiguous semi-circular. sections; an inlet duct for one fluidconnecting at one side of one partition lwith a semi-circular section'of one annular passage and at the other side of said partition with asemi-circular section of the adjacent annular passage; an inlet duct fora second iluid connecting with those sections of both said annularpassages that are contiguous to the sections con- .neeted with saidilrst mentioned inlet duct;

similarly connected fluid outlet ducts; means forming a channel locatedadjacent the inner one of said annular passages and concentrictherewith: and inlet and outlet ducts for circulating fluid through saidchannel in heat exchange relationship simultaneously with said one iiuidowing in a semi-circular section of the adjacent annular passage andwith said other fluid nowing in the contiguous semi-circular section ofsaidsame annular passage; and a spiral dellector 4disposed in saidannular channel for causing a volume of iiuid flowing through saidchannel at either side of its longitudinal axis to be transposed aboutthe latter so that as said iluld volume progresses longitudinally ofsaid exchanger it is in heat exchange relationship with thetwo fluids inthe sections of the adjacent passage.

`10. A heat exchanger particularly for gaseous media having a passageextending from end to end thereof parallel to its longitudinal axis;transverse partitions in and extending from. end to end of said passageand subdividing itinto a plurality of contiguous sections for flow ofiluid in parallel streams longitudinally of said exchanger; an inletduct for one huid connecting individually with alternate sections ofsaid passage at one end of said exchanger; an inlet duct for a secondiluid connected with the intermediate sections of said passage at theopposite end A of said exchanger; similarly connected fluid outlet ductsconnected to the other ends of said alternate and intermediate sections;a channel located adjacent said passage and separated therefrom by acommon intervening wall; and inlet and outlet ducts connecting with saidchannel at opposite ends thereof for circulating a third fluidtherethrough in heat exchange relationship with the rst and secondfluids in the sections of said passage.

11. A heat exchanger particularly for gaseous media comprisingconcentric walls forming an annular passage; transverse partitions inand extending from end to end of said passage and sub-dividing it into aplurality of contiguous sections for ilow of uid longitudinally of saidexchanger parallel to its axis; an inlet duct for one iluid connectingindividually with alternate sectionso!saidpassageatoneendofsaidexchanger; an inlet duct for a second fluidoonnected with the intermediate sections of said passage at the oppositeend of said exchanger;

Y similarly connected nuid .outlet duets connected to the other ends ofsaid alternate and intermediate sections: means forming a channellocated adjacent said annular passage and separated therefrom by acommon intervening wall; and inlet and outlet ducts connecting with saidchannel at opposite ends thereof for circulating aVA third iluldtherethroughin heat exchange relationship with the iirst and second uidsflowing in the sections of said passage.

12. A heat exchanger particularly for gaseous media comprising; acylindrical casing interiorally divided by concentric wall membersextending longitudinally thereof to form a pair of forming a channellocatedadjacent the inner one .of said annular passages' and concentrictherewith; inlet and outlet ducts connecting with said channel atopposite ends thereof; and deiiecting means dlspod 'across said channeland extending spirally from end to end thereof for directing the fluidin said channel in a stream. successively in contact with wall portionsthereof in heat exchange relation with uid flowing both semicircularsections of adjacent 1: 1

" SVEN' HOIM.

PER HILMER. KARLSSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 621,537 Ostergren et al. Mar.'21, 1899 1,763,012 Shipman June 10, 1930 2,057,804 Twomey f Oct. 20,1936 2,186,077 Noyes Jan. 9, 1940 FOREIGN PATENTS Number Country Date320,279 Great Britain Oct. 10, 1929 326,278 Great Britain Mar. 13, 1930538,391 Great Britain July 31, 1941 615,919 France Jan. 19, 1927

